Lípa, the lime tree or linde (tilia), is the national tree of the Czech Republic. It is a feminine symbol of life that reflects the myth of queen Libuše as the female founder of the Czeque nation.

Likewise, literature constitutes the collective memory of the Czech nation and vital part of its cultural progression. Together they are intertwined in perpetual growth and evolution. In this respect the national tree provides a befitting and exciting image, organisation and structure for the aspiration of this scheme to both embody and house this cultural dynamic.

Our proposal deploys the evocative image of the lime tree in a threefold manner:

- to provide a sensous image of cultural and literary evolution, growth and proliferation engendered by Czech literary tradition and production;

- to embrace the breathtaking landscape of Prague and the Moldau valley so as to extend and interweave it smoothly into the built fabric of the city;

- to evolve a unique tectonic that mediates between urban fabric and living nature. In doing so, the design takes inspiration from the late gothic Vladislav Hall (1493-1502) with its unique and immaculate starshape rip vault by Benedikt Ried, which fuses the tectonic and the organic in a spectacular and stately manner.

The building is organised in three distinct, but interconnected volumes that together form a very large tree-like form. The central volume constitutes the trunk, which organises a smooth connection between Milady Horákové Avenue and Letenské park. The cantilevering volumes provide the treetop that enable the unique spatial experience of inhabiting a vast tree space.

II. Location of the National Library on the designated Site

The design seeks to provide at the same time a singular monolithic and monumental appearance for one of the key buildings of Czech culture, as well as a continuous and gradient spatial experience of the beautiful picturesque landscape of the site. The vast tree-like form and its particular space adheres to both aspirations. It is both contained and open, confined and continuous, providing the qualities that satisfy both aims and provide a unique and stunning spatial experience for the visitor and the employee alike.

We understand the scheme as one of several landscaped sites that together form a network of adjacent events and scenic spots that make the larger site attractive in its own right. It is therefore important to provide suitable links and views between the various locations of the landscape network.

The orientation of the elongated volumes that make up the scheme is generally north-south, connecting the urban edge of Milady Horákové Avenue smoothly into the vast landscape of Letenské park. The volumes shift, however, so as to organise the directions of approach and circulation that are anticipated by the competition brief, to and from the centrally located entrance and reception area, as well as to frame key views across the site and the city.

The library and office volumes are cantilevered such that a continuous public landscape is provided on the ground floor level, west of the National Library volume. Moreover, the two cantilevering volumes pertrude beyond the central supporting volume along Milady Horákové Avenue in order to provide the experience of buoyant monolithic volumes that form the edge of an urban block, while maintaining the continuous landscape on ground level.

Vehicular access to the site is provided at the southern section of the western perimeter, with a ramp into and out of the basement levels, which is integrated into the modulated terrain.

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III. Description of operational and spatial relations inside the National Library

The tree-like spatial and tectonic scheme is reflected in the programmatic and circulatory organisation of the National Library. Two cantilevering volumes are supported by the building volume that contains the national archive. This organisation delivers architectural expression to the notion that the national archive is the foundation of Czech literary production. Contemporary literature originates and extends from its shelves.

The trunk of the abstract tree is formed by the national and parliamentary libraries from which the internal functions of the libary branch out as cantilevering volumes. Public space is articulated both as a continuous public landscape around the trunk of the tree, sheltered by its branches, and as a treehouse at the highest point of the tree, granting spectacular views of the surrounding landscape, as well as Prague’s historical centre and monuments.

The continuous landscape on the ground floor level provides for 24 hour public activities such as exhibitions, public literature readings, book shopping and the cafe, which are smoothly distributed on the articulated datum. Moreover, the terrain articulation serves to effectively guide visitor flows to the main public core(s), while enabling universal accessibility of the continuous landscape throughout the site.

Public functions that are of urban character, the bookshop and the exhibition space are located to the north of the landscaped ground floor, addressing the intended boulevard character of Milady Horákové Avenue. The cafe is located to the south, benefiting from the presence of the park.

Library functions and offices are clearly separated by the volume of the National Library, each into their own cantilevering volume. The library functions in the cantilevering volume are predominantly oriented towards the west and the south, including the main library hall and the reading rooms, thus taking advantage of the views of the park and the national monuments in the centre of the city. This principle reaches its climax with the restaurant, panorama terrace and lecture theatres on the top floor, providing spectacular views of Prague above the high tree-line of Letenské Park.

The National Library volume is conceived of as an opaque shrine of knowledge that provides selected and highly controlled glimpses of the activities it houses to the public, in the form of a ramped episodical pathway along the western edge of the volume that faces the public part of the building.

The office block houses from bottom to top the Acquisition Division, the Collections Management and Preservation Division and the National Bibliography and Cataloguing Division. Offices are organised with the intention to provide for a generous space that accommodates changes in the workflow and arrangement of activities..

IV. Technical description of Structural Design

The cantilevering volumes are supported by the volume that contains the national archive. The library and office volumes are cantilevered from it, supported by five large frames that are arranged in a fan-shape. The unique branching structure that envelopes and supports the cantilevering volumes reinforces the image of the vast tree-space of the library. The form-generation of the branching structure evolved from a digital analysis of the force flow that resulted from the load-case of cantilevering the two volumes. The load vectors are articulated as a branching system, which gradually becomes thinner towards the edges of the cantilevers. The self-similar character of the branching system enables a simultaneously differentiated yet rationalised tectonic that deploys a range of profile families for the structure of the scheme.

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V. Technical description of Materials and Environmental Performance

The material used for the building envelope consists of high-value insulation glass with light deflecting prismatic or fin systems in the façade and translucent light diffusing glass in the roof surface, to provide desired light conditions and to avoid direct daylight throughout the library while facilitating the spectacular views afforded by the site.

The perimeter wall of the National Library volume consists of reinforced concrete. The screen that separates the ramped episodical pathway from the vertical space between the supporting volume and the cantilevers consists of a glass with a non-uniform print pattern that maintains opacity from the outside and transparency from the ramp, such as to provide exciting views of the interior.

The scheme deploys a spatial arrangement that utilises the stack effect for natural ventilation of the ground floor public space. Warm air rises in the space between the cantilevers and the volume of the National archive and is released on the roof level, which, in turn, brings fresh cooler air from into the building from its perimeter. The building tilts towards the western edge to take advantage of the prevailing western winds, so as to accelerate air exchange by means of the Venturi Effect. Likewise the two cantilevering volumes are ventilated. The volume of the National Archive is fully environmentally controlled to provide the required constant 18 degrees centigrade and 50% relative humidity.